The number of simultaneous users a repeater forming part of a wireless network can support is often determined by the amount of uplink transmit signal power that is available at the donor antenna of the repeater. In the case of a CDMA or UMTS systems for example, all users that have active transmissions must share the available uplink power. If the users require more uplink power than is available, the transmission from the users cannot reach the base station and this may result in dropped calls or very poor uplink data throughput.
What makes this issue particularly acute is the fact that the user may see 5 bars on his phone's signal strength indicator and yet his calls cannot go through. This is due to the fact that in the downlink direction, the user may be closer to the server antenna and hence is receiving a strong signal at the input to his phone. When this condition occurs, it is not possible to deliver a good quality of user experience to the end user and furthermore, this leads to an increase in support calls to the mobile operator or repeater vendor.